The present invention relates to a helium enclosed compressor, and particularly, to one suitable for a helium enclosed compressor in which a motor section having coil ends is housed within an enclosed vessel filled with a helium gas.
In a conventional helium enclosed compressor, a helium gas is used as a working gas, a compressor section and a motor section are arranged vertically and housed within an enclosed vessel, the inside of the enclosed vessel is partitioned into a discharge chamber and a motor chamber by a frame, a first rectangular passage which allows the discharge chamber to communicate with the motor chamber is provided between an outer peripheral surface of the frame and an inner wall surface of the enclosed vessel, and a second passage which allows an upper motor chamber to communicate with a lower motor chamber is provided between an outer peripheral surface of the stator and the inner wall surface of the enclosed vessel. Also, the compressor section is adapted such that a stationary scroll and an orbiting scroll are made to mesh with each other while their wraps face the inside, and the orbiting scroll is made to orbit, thereby sucking the helium gas from a suction port of an outer peripheral portion of the stationary scroll, and discharging the helium gas into the motor chamber through the inside of the discharge chamber from a discharge port of a central portion of the stationary scroll. Additionally, the helium enclosed compressor includes an oil injection mechanism section which connects an oil injection pipe for cooling the helium gas to an oil injection port provided in the panel of the stationary scroll through the enclosed vessel, and an inverter which controls the number of rotations of the motor section.
As a document relevant to the helium enclosed compressor, for example, JP-A-2006-29251 is mentioned.
In the helium scroll compressor, the peripheries of the coil ends are full of a helium gas. Therefore, it turned out that there are problems inherent in helium applications that corona discharge occurs easily in a helium gas atmosphere, and thereby, the insulating property of the motor coil ends deteriorates. Particularly when the number of rotations of the motor section is controlled by an inverter, a high voltage surge voltage is generated on the side of the inverter, and the high surge voltage acts on the coil ends. Therefore, the corona discharge occurs easily.
However, in the conventional helium scroll compressor, a varnish-treated layer formed on the surface of a coil which constitutes the coil ends was a monolayer, and it could not be said that prevention of a corona discharge was fully considered.